London’s accreted from immigrant generations – Jewish, Caribbean, Bengali, Pakistani, Indian, Chinese, Irish, Polish, Roma, and endlessly on. It is saturated with decades of effort, the grind of antiracist activists remembered in the city’s matter: the Claudia Jones Organisation, the CLR James Library. In the built world – the Brick Lane Mosque, previously a synagogue, before that a church – in clothes and music, in London’s rapid slang, in the withering of hate-filled chants on football terraces, in attitudes transformed from three, two decades ago, in all the mixed friendships and love affairs, down to its deeps and to Londoners’ joy and fortune, London is the most and most successfully multicultural city in Europe.

Diasporas have sustained us. It’s a terrible cliché, multiculturalism through food, but there’s a reason it’s what we reach for. Smart restaurants like St John have rehabilitated English fodder, glorying in pork, blackberries, eulogising offal. Fine. If you’re of a certain age and grew up here, you remember that aside from the lucky, rich or recent immigrant families aside, we had no food. We gnawed bread like bleached plastic, cheese like soap. We yowled, a hungry people. New Londoners took pity before the rest of us succumbed to malnutrition and misery, and shared their cuisines. Indian, Jamaican, whatever – name a culinary tradition, it won’t be too far to find, near greasy spoons keeping the faith. Each new group of incomers brings something – now Polish food has mainstreamed, and there’s dense bread in the corner shops, krufki in supermarkets.

Racism, of course, endures, adapts. According to the exigencies of ideology, casts around for one, then another first-choice hate. Jews in the 1930s, then black people, then Asians. For the past 10 years, Muslims in particular have worn the bulls-eye. If they’re women who cover their hair, those few who veil entirely or those who chat into scarf-tucked phones, the hijab hands-free, their choice of headgear is bizarrely troublesome to those whose business it is not. The government’s official counterterror strategy includes asking lecturers to report depressed Muslim students. Hate crimes against Muslims rise, fuelled, researchers at the University of Exeter suggest, by the mainstreaming of Islamophobia among politicians and in the media. You can say shocking, scandalous things about Muslims, and opinion-makers do, then push out their chins as if they’ve been brave.

Feeding on that disgrace, Britain is seeing a mutation of its ‘traditional’ fascism into a form fixated on these new scapegoats. Emerging from groups like the British National Party and football hooliganism, the English Defence League aims its spite squarely at Muslims. It follows a familiar trajectory of intimidation: it tries to march in ‘Muslim’ areas. But it has taken a few unusual turns, too, showing off a (very) few members of colour, Jewish members, gay members. Pitching for a ‘liberal’ fascism.

But London is London. ‘Their situation in London is incredibly weak,’ says Martin Smith, a leader of Unite Against Fascism. ‘Because London’s so integrated,’ he adds enthusiastically, ‘you can literally go from estate to estate and it’s black, white, mums and dads, mixed, all that.

‘I think with migrants,’ he continues, pausing slightly, ‘you can get what I would call racist sentiments developing, even among Blacks, Asians.’ Smith knows this fight. He’s optimistic but not relaxed. These are not easy times. The city shakes. ‘There could be, I suppose — panic issues could develop around that. I wouldn’t rule that out in London. I think it would be hard but I wouldn’t rule it out.’